Leaders of both parties dueled Wednesday over which side was truly interested in helping women as the Senate approached a vote on campaign-season legislation curbing paycheck discrimination based on a worker's gender.

WASHINGTON — Leaders of both parties dueled Wednesday over which side was truly interested in helping women as the Senate approached a vote on campaign-season legislation curbing paycheck discrimination based on a worker's gender.

In a showdown roll call expected Wednesday, Republicans seemed likely to derail the measure. Democrats were hoping to reap political dividends anyway by driving up turnout in this fall's congressional elections by women voters, who historically lean more Democratic than men.

"For reasons known only to them, Senate Republicans don't seem to be interested in closing wage gaps for working women," said Senate Majority Leader Harry Reid, D-Nev., as the day's debate began.

Reid's GOP counterpart faulted him for blocking Republican proposals that would cut taxes, allow more flexibility for workers' hours and take other steps they said would protect jobs and help employees. In contrast, the Democratic bill would open the door for frivolous, expensive workers' lawsuits against companies, Republicans say.

"It's time for Washington Democrats to stop protecting trial lawyers and start focusing on actually helping the people we were sent here to represent," said Senate Minority Leader Mitch McConnell, R-Ky.

Though Democrats run the Senate, they control 55 votes and needed at least five Republicans to halt a GOP blockade against it — a number they seemed unlikely to reach.

The battle was suffused with the politics of an election year in which Republicans could capture Senate control and are expected to retain their hold on the House. Senate Republicans derailed the bill in 2010 and 2012, the last two election years.

On Tuesday, Democrats all but dared Republicans to resist the legislation, which would make it harder for companies to pay women less than men for the same work and easier for aggrieved workers to sue employers.

"Republicans stand opposed to pay equity at their own peril," said Sen. Chuck Schumer of New York, the No. 3 Senate Democrat. He pointedly added, "We're going to come back to this issue several times this year."

Countered Sen. John Thune of South Dakota, a member of the GOP leadership, "It's very clear what this is about, and that is very simply trying to score political points."

In a year when polls show little enthusiasm among Democratic voters, congressional Democrats were also casting the issue as a crucial one for the middle class because so many families rely on female wage-earners.

Republicans, with strong backing from the U.S. Chamber of Commerce and other business groups, said the measure would tie the hands of employers.

Joined by Democratic lawmakers and Lilly Ledbetter at the White House, President Barack Obama took a swipe at the GOP. Ledbetter's claims of pay inequity by her employer led to the 2009 anti-discrimination statute bearing her name, the first bill Obama signed as president.

"Republicans in Congress have been gumming up the works. They've been blocking progress on this issue," said Obama, adding later: "America, you don't have to sit still. You can make sure that you're putting some pressure on members of Congress about this issue."

Republicans said the bill would make it hard for companies to award merit pay or offer flexible work hours in exchange for lower pay and expose employers to costly, frivolous lawsuits.

McConnell cited statistics showing how women's income has fallen and their poverty rate increased under Obama.

"It's important to kind of put in place the record of the current administration with regard to women," McConnell said. Obama took office during the worst recession since the Great Depression of the 1930s.